This invention relates to trailer tippers and, more particularly, to low-profile, portable trailer tippers.
Trailer tippers and low-profile, portable trailer tippers are known in the art. Examples of a few such tippers are disclosed in U.S. Pat. Nos. 5,458,451 and 6,019,568, the disclosures of which are incorporated herein by reference. Prior art tippers offer a number of advantages and make it relatively quick and easy to unload dumpable material from a trailer. Still, these tippers suffer from a number of shortcomings. For example, tippers are relatively large, cumbersome pieces of equipment. Delivery and assembly of such tippers can be difficult, time-consuming, and expensive. For example, in some instances, wheels will be placed on the tipper for delivery and removed after the tipper is put in place at the site at which it will be used. Putting on and taking off wheels is a time-consuming, labor intensive task. There is also the question or problem of how and where to store the wheels after their removal. Further, if the wheels are removed, moving or repositioning the tipper requires the user to find and put on the wheels or requires the user to drag the tipper around without wheels.
Further, prior art tippers typically have the rear wheel axles attached directly to the sub-frame similar to the configuration shown in FIGS. 1 and 2. This results in the wheel assembly being substantially fixed relative to the sub-frame. If all of the wheels are positioned so as to contact the ground on a level surface, then, when the tipper is being transported and moves across uneven surfaces, the load would be shifted more to one set of outside wheels and less or none to the opposite set. When the tipper is set-up on-site and the front of the tipper is rotated to a down position during use, the wheels are also rotated relative to the ground surface. This causes an uneven distribution of the tipper weight to each axle of the wheel assembly. The front axle and wheels are loaded more heavily than the rear axle and wheels. In many instances, the rear wheels bear little or none of the load and are in fact lifted from the ground. At a site with soft ground or footing material this would cause the front wheels to sink and dig into the ground, resulting in more effort in pulling it from one location to another at the same site.
Present tippers that use the fixed wheel assembly also typically have the wheels located inside of the sub-frame. The narrow wheel assembly width provides less stability and places a greater load on the rear stabilizers or outriggers when the tipper is in operation. During transport, this more narrow width reduces the lateral stability and tracking capability of the tipper. Present tippers using a more narrow width sub-frame also have the walkways and handrails attached to the deck which results in an increase in weight that must be lifted by the main cylinders.
Prior art portable trailer dumpers or tippers also typically attach stabilizers or outriggers to the sub-frame using removable pins, such as seen in FIGS. 3 and 4. During transport to the site where the tipper is to be used these outriggers must be removed from the sub-frame and shipped separately. This increases the amount of time required for setup and takedown when the tipper either arrives at or prepares to leave the site.
Prior art tippers also typically have adjustable backstops that employ movable backstop members having little or no flexibility. The movable backstop member is typically pivotally connected to the deck so that it swings up or down to accommodate only two different lengths of trailers during the dumping operation, such as seen in FIGS. 5 and 6. This type of movable backstop member is located in front of the fixed backstop and in the down position allows shorter trailers to be dumped. When dumping a longer trailer, the movable backstop member is rotated upward about a pivot located on one side of the tipper deck. This results in a potentially unsafe condition since the weight of the movable backstop member is suspended over the side of the tipper. In windy conditions, the movable backstop member may also act somewhat like a sail, catching wind and decreasing the stability of the tipper. This type of adjustable backstop also does not provide the flexibility to variably adjust the distance of the movable backstop member from the back of the deck on the fly to accommodate trailers of non-standard lengths or to accommodate trailers with dollies or the like.